Beach RC says... This is the Ultimate Racing air filter set and is intended for use with the majority of 1:8 Off Road cars you can find on the market. It includes the new dual-stage foam, a high-density foam element and a pre-filter. The high-density foam captures the smallest particles to keep your engine in top condition, yet it allows plenty of airflow so the engine can produce maximum power. You should always oil the inner filter element, but if the track is very dry and dusty it is recommend that you also oil the outer pre-filter element. This package includes all the components necessary to build one complete air filter set. Air filter oil not included.